Specifically, Nielsen found that feature phones, which researchers defined as "devices with no touchscreen, QWERTY keypad or operating system" are far more dominant in India and Russia, covering 80 percent and 51 percent of mobile users, respectively.

That's definitely not the case in the United States. For example, in another report from Nielsen in 2011, the research firm reported that nearly 60 percent of all new cell phones being sold at that time were smartphones.

Other analysts are already predicting big things for smartphones across emerging markets.

Canalys predicted on Thursday that developing markets will see smartphone growth of at least 22.5 percent this year -- particularly within the BRIIC group of Brazil, Russia, Indonesia, India and China.

China, incidentally, was the only emerging market listed in the Nielsen update where smartphones are now more dominant than feature phones.

That's not surprising as China continues to overtake the United States as a top tech market in a number of different ways. For instance, Apple CEO Tim Cook recently said that he expects China to be the iPhone maker's number one market at some point.